Microelectronic packages with leadframes, including leadframes configured for stacked die packages, and associated systems and methods

ABSTRACT

Microelectronic packages with leadframes, including leadframes configured for stacked die packages, and associated systems and methods are disclosed. A system in accordance with one embodiment includes a support member having first package bond sites electrically coupled to leadframe bond sites. A microelectronic die can be carried by the support member and electrically coupled to the first packaged bond sites. A leadframe can be attached to the leadframe bond sites so as to extend adjacent to the microelectronic die, with the die positioned between the leadframe and the support member. The leadframe can include second package bond sites facing away from the first package bond sites. An encapsulant can at least partially surround the leadframe and the microelectronic die, with the first and second package bond sites accessible from outside the encapsulant.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims foreign priority benefits of SingaporeApplication No. 200604777-3 filed Jul. 17, 2006.

TECHNICAL FIELD

The present disclosure is directed generally to microelectronic packageswith leadframes, including leadframes configured for stacked diepackages, and associated systems and methods.

BACKGROUND

Packaged microelectronic assemblies, such as memory chips andmicroprocessor chips, typically include a microelectronic die mounted toa substrate and encased in a plastic protective covering. The dieincludes functional features, such as memory cells, processor circuitsand interconnecting circuitry. The die also typically includes bond padselectrically coupled to the functional features. The bond pads areelectrically connected to pins or other types of terminals that extendoutside the protective covering for connecting the die to busses,circuits, and/or other microelectronic assemblies.

In one conventional arrangement, the die is mounted to a supportingsubstrate (e.g., a printed circuit board), and the die bond pads areelectrically coupled to corresponding bond pads of the substrate withwirebonds. After encapsulation, the substrate can be electricallyconnected to external devices with solder balls or other suitableconnections. Accordingly, the substrate supports the die and provides anelectrical link between the die and the external devices.

In other conventional arrangements, the die can be mounted to aleadframe that has conductive leadfingers connected to a removableframe. The frame temporarily supports the leadfingers in positionrelative to the die during manufacture. Each leadfinger is wirebonded toa corresponding bond pad of a die, and the assembly is encapsulated insuch a way that the frame and a portion of each of the leadfingersextends outside the encapsulating material. The frame is then trimmedoff, and the exposed portions of each leadfinger can be bent to formpins for connecting the die to external components.

Die manufacturers have come under increasing pressure to reduce the sizeof their dies and the volume occupied by the dies, and to increase thecapacity of the resulting encapsulated assemblies. One approach toaddressing these issues has been to stack multiple dies on top of eachother so as to make increased use of the limited surface area on thecircuit board or other element to which the dies are mounted. Onedrawback with some of the existing stacking techniques is that one ofthe dies may fail during a following-on test process. When this occurs,the entire package, including operational dies, is typically discardedbecause it is not practical to replace a single die within a package.Another potential drawback is that the stacked dies can occupy asignificant volume in a vertical direction, which can in some casesreduce the benefits associated with stacking the dies. Accordingly,there is a need for techniques that reduce the thickness of stacked diepackages, and improve the reliability of such packages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially schematic, cross-sectional side view of a systemthat includes microelectronic die packages configured and stacked inaccordance with an embodiment of the invention.

FIGS. 2A-2F illustrate a process for forming a leadframe in accordancewith an embodiment of the invention.

FIGS. 3A-3G illustrate a process for encapsulating a microelectronic dieand a leadframe in accordance with an embodiment of the invention.

FIG. 4 is a partially schematic, cross-sectional side view of a packagehaving a microelectronic die and leadframe configured in accordance withanother embodiment of the invention.

FIG. 5 is a partially schematic, top plan view of a microelectronic diecarried by a support member and connected to a leadframe in accordancewith another embodiment of the invention.

FIG. 6 is a partially schematic, cross-sectional side view of a packagethat includes a microelectronic die coupled to a support member with aleadframe and solder balls in accordance with another embodiment of theinvention.

FIG. 7 is a partially schematic, cross-sectional side view of a packagethat includes two stacked microelectronic dies electrically coupled to aleadframe in accordance with another embodiment of the invention.

FIG. 8 is a partially schematic, cross-sectional side view of a packagethat includes two stacked microelectronic dies coupled to a singleleadframe in accordance with still another embodiment of the invention.

DETAILED DESCRIPTION

The present disclosure relates generally to microelectronic packageshaving leadframes, including leadframes configured for stacked packages,and associated systems and methods. For example, one system includes asupport member having first package bond sites and leadframe bond sitesthat are electrically coupled to the first package bond sites. Amicroelectronic die carried by the support member is electricallycoupled to the first package bond sites. The leadframe can be attachedto the leadframe bond sites and can extend adjacent to themicroelectronic die, with the microelectronic die positioned between theleadframe and the support member. The leadframe can have second packagebond sites facing away from the first package bond sites. An encapsulantat least partially surrounds the leadframe and the microelectronic die,with the first and second package bond sites accessible from outside theencapsulant.

In a further particular aspect, the support member, the microelectronicdie, the leadframe and the encapsulant form a first microelectronicpackage, and the system can further include a second microelectronicpackage having a configuration generally similar to that of the first,with the second microelectronic package stacked on the first, and withthe first package bond sites of the second microelectronic packageelectrically connected to the second package bond sites of the firstmicroelectronic package. In yet further aspects, one or more of thepackages can itself include multiple microelectronic dies positionedbetween the corresponding leadframe and the corresponding supportmember.

Other aspects are directed to a leadframe for electrical coupling to amicroelectronic die. The leadframe can include a conductive frame and aplurality of conductive leadfingers that are connected to and extendinwardly from the frame. Individual leadfingers can have a leadfingersurface that faces in a first direction and is located in a leadfingerplane. The individual leadfingers can further have an electricallyconductive bond site with a bonding surface that is offset away from theleadfinger plane in the first direction. Leadfingers having such aconstruction can be positioned within microelectronic packages, with theoffset bonding surfaces accessible from outside the encapsulant of thepackage, so as to permit coupling to the microelectronic die within thepackage.

Further aspects are directed to methods for making a microelectronic diesystem. One such method can include carrying a microelectronic die witha support member having first package bond sites and leadframe bondsites that are electrically coupled to the first package bond sites. Themethod can further include electrically coupling the microelectronic dieto the first package bond sites, and positioning the leadframe adjacentto the microelectronic die, with the microelectronic die located betweenthe leadframe and the support member, and with second package bond sitesof the leadframe facing away from the microelectronic die. The methodcan further include electrically connecting the leadframe to theleadframe bond sites, at least partially surrounding the leadframe andthe die with an encapsulant, and allowing access to the first and secondpackage bond sites from outside the encapsulant. Accordingly, thepackage can be coupled to external devices, and can be stacked toimprove device density.

In particular aspects, allowing access to the second package bond sitescan include removing encapsulant adjacent to the package bond sites,grinding the encapsulant to expose the package bond sites, and/orrestricting the encapsulant from being disposed adjacent to the secondpackage bond sites. In further aspects, the support member can include acircuit board, and can be the only support member within theencapsulant.

Many specific details of certain embodiments of the invention are setforth in the following description and in FIGS. 1-8 to provide athorough understanding of these embodiments. One skilled in the art,however, will understand that the present invention may have additionalembodiments, and that the invention may be practiced without several ofthe details described below.

FIG. 1 is a partially schematic, cross-sectional side view of a system100 that includes stacked microelectronic packages configured inaccordance with an embodiment of the invention. The system 100 caninclude multiple stacked packages 110 (e.g., two packages, shown as afirst package 110 a and a second package 110 b), each having a generallysimilar configuration. For example, each package 110 can include asupport member 130 (e.g., a circuit board), a microelectronic die 120(e.g., a memory chip or a processor chip), and a leadframe 140 thatprovides for electrical connections between the microelectronic die 120and other devices, including, but not limited to, other stackedpackages.

Referring to the first package 110 a, the support member 130 can bothcarry the microelectronic die 120 and provide electrical communicationto and from the die 120. Accordingly, the support member 130 can havesupport member bond sites 133 that are electrically coupled tocorresponding die bond sites 121 of the die 120. In an embodiment shownin FIG. 1, wirebonds 122 provide the electrical coupling between the diebond sites 121 and the support member bond sites 133, and in otherembodiments, other electrical couplings (e.g., solder balls) form thislink. The support member 130 can also include internal circuitry 131that connects the support member bond sites 133 with other bonds sites,including first package bond sites 112 and leadframe bond sites 132. Thefirst package bond sites 112 provide communication to other devicesexternal to the package 110 via solder balls 101 or other electricallyconductive couplers. Some of the first package bond sites 112 arelocated out of the plane of FIG. 1, as indicated by dashed lines. Theleadframe bond sites 132 provide communication to second package bondsites 113 via the leadframe 140. Accordingly, the die 120 cancommunicate with external devices 103 via the first package bond sites112 and/or the second package bond sites 113.

Each package 110 can include an encapsulant 111 that surrounds andprotects the internal components, including the wirebonds 122 and theleadframe 140. The encapsulant 111 can be positioned and/or configuredwith the first package bond sites 112 and the second package bond sites113 exposed for electrical coupling to other components. The othercomponents can include other packages 110 (e.g., when the packages 110are stacked), and/or external circuit boards, and/or any of a widevariety of intermediate and/or end-user devices, such as computingdevices, communication devices, testing devices or other electroniccomponents.

Stacked packages can, but need not have generally similarconfigurations. For example, as shown in FIG. 1, the two packages 110 a,110 b can each have a generally similar arrangement of internalcomponents, but the second package 110 b can have its encapsulant 111arranged so as to cover over the second package bond sites 113.Accordingly, the second package 110 b can be located at the top of astack of packages (as shown in FIG. 1), or it can be used singly. Inother embodiments, the second package 110 b can have an encapsulantarranged identically to that shown for the first package 110 a, but caninclude an optional covering 114 (shown in dashed lines in FIG. 1) toprotect the otherwise exposed second bond sites 113. In still furtherembodiments, the system 100 can include dissimilar packages stacked ontop of each other.

FIGS. 2A-2F illustrate a representative process for forming a leadframe140, such as the one shown in FIG. 1. FIG. 2A illustrates the centralportion of the leadframe 140, including leadfingers 141 that extendinwardly toward each other from a surrounding frame (described laterwith reference to FIG. 2F). Each leadfinger 141 can include a firstleadfinger surface 142 a and a second leadfinger surface 142 b facingopposite from the first leadfinger surface 142 a.

FIG. 2B illustrates a process for forming the second package bond sites113 at the leadfingers 141. In one aspect of this embodiment, the secondpackage bond sites 113 are formed by etching or otherwise removingmaterial from the first leadfinger surface 142 a so as to leaveprojections having a bonding surface 143 that is generally parallel tothe recessed first leadfinger surface 142 a, but offset away from thefirst leadfinger surface 142 a. Accordingly, the first leadfingersurface 142 a is located generally in a leadfinger plane, and thebonding surface 143 is offset outwardly away from the leadfinger plane.In a particular embodiment, the bonding surface 143 is generally flat,but it can have other shapes in other embodiments. In FIG. 2C, materialcan be removed from the first leadfinger surface 142 a, the secondleadfinger surface 142 b, and/or the bonding surfaces 143 to reduce theoverall thickness of the leadframe 140. In FIG. 2D, an adhesive 144 isattached to the second leadfinger surface 142 b in preparation forbonding the leadframe 140 to a corresponding microelectronic die.

FIG. 2E is a cross-sectional side elevation view of an entire leadframe140, with an adhesive 144 attached, taken substantially along line 2E-2Eof FIG. 2F. Referring to FIGS. 2E and 2F, the leadframe 140 can includea frame 145 from which the leadfingers 141 extend. Each leadfinger 141has a single second package bond site 113, but adjacent leadfingers 141have different lengths and are offset relative to each other to properlyalign neighboring second package bond sites 113. The leadfingers 141 canalso be bent as shown in FIG. 2E so as to fit over a correspondingmicroelectronic die, with the frame 145 holding the leadfingers 141 inplace during the attachment process. In a representative embodiment, theleadframe 140 is generally self-supporting. For example, although it isrelatively thin and flexible, it can keep its shape, and is thereforedifferent than typical internal redistribution layers, which are formeddirectly on or in a microelectronic die or support member using adeposition process.

FIGS. 3A-3G illustrate a process for attaching the leadframe 140 to amicroelectronic die 120, and completing the formation of the resultingpackage. Beginning with FIG. 3A, a microelectronic die 120 is attachedto the support member 130 so that the die bond sites 121 are alignedwith an aperture in the support member 130. Wirebonds 122 are thenconnected between the die bond sites 121 and the support member bondsites 133. The support member bond sites 133 are in electricalcommunication with the leadframe bond sites 132, as discussed above withreference to FIG. 1. Each of the leadframe bond sites 132 can optionallyinclude a solder ball 134 or other arrangement for attaching to theleadframe and providing electrical signals to the leadframe.

FIG. 3B illustrates the leadframe 140 positioned over themicroelectronic die 120 in preparation for attaching it to both thesupport member 130 and the microelectronic die 120. The microelectronicdie has a first surface 125 facing toward the support member 130, and asecond surface 126 facing toward the leadframe 140. The leadframe 140can be attached to the microelectronic die 120 with the adhesive 144,and the leadframe 140 can be attached and electrically coupled to thesupport member 130 via the solder balls 134. Accordingly, unlike manyexisting applications of leadframes, the illustrated leadframe 140 doesnot have wirebonds attached to it. A suitable reflow process and/orcuring process can be used to form the foregoing attachments to theleadframe 140. For purposes of illustration, the reflowed solder balls134 and cured adhesive 144 are not shown in the following figures.

FIGS. 3C is a partially schematic, cross-sectional side view of thesupport member 130 and the leadframe 140, as the outer frame 145 of theleadframe 140 is separated from the rest of the leadframe 140 along trimlines 146. FIG. 3D is a plan view of the arrangement shown in FIG. 3C.Once the outer frame 145 has been separated, the leadframe 140, thesupport member 130, and the microelectronic die 120 can be encapsulated,as shown in FIG. 3E. In a particular aspect of this arrangement, thesupport member 130, with the microelectronic die 120 and the leadframe140 attached, is placed in a mold and the encapsulant 111 is injected inthe mold so as to cover the second package bond sites 113. As shown inFIG. 3F, the portion of the encapsulant 111 covering the second packagebond sites 113 can then be removed to expose the second package bondsites 113. For example, a grinding process, laser removal process, orother appropriate process can be used to remove the encapsulant 111 downto a removal line 115. The encapsulant 111 can be removed from acrossthe entirety of the upper surface of the package, or it can beselectively removed from just the second package bond sites 113, forexample, to form “wells” that contain the solder balls or otherelectrical couplers that are later placed at the second package bondsites 113.

In another arrangement, the step of removing the portion of theencapsulant 111 overlying the second package bond sites 113 can beeliminated by preventing the encapsulant 111 from being disposed on thesecond package bond sites 113 in the first place. For example, the moldin which the first package 110 a is placed during the encapsulationprocess can include pins or other removable structures that cover overthe second package bond sites 113 and prevent the encapsulant 111 fromcontacting and adhering to the second package bond sites 113. Also, asdiscussed above with reference to FIG. 1, if the particular package neednot have the second package bond sites 113 exposed (e.g., if the packageis intended to be placed at the top of a package stack), then theoverlying encapsulant 111 need not be removed.

FIG. 3G illustrates both the first package 110 a and the second package110 b described above with reference to FIG. 1. Solder balls 101 havebeen attached to the first package bond sites 112 of each package 110 a,110 b. Prior to attaching the packages 110 a, 110 b to each other, eachpackage can be separately tested using a probe 102 (shown schematicallyin FIG. 3G) or another device that communicates with the internalmicroelectronic die 120 via the first package bond sites 112 and/or thesecond package bond sites 113. In this manner, each of the packages 110a, 110 b can be electronically tested prior to the stacking operation.An advantage of this arrangement is that the likelihood for stacking a“bad die” with a “good die” is reduced or eliminated. Accordingly, theprocess of stacking the packages 110 a, 110 b into a final assembly canbe completed using only known good packages.

The process for stacking the packages 110 a, 110 b can include placingthe second package 110 b on the first package 110 a, with the firstpackage bond sites 112 of the second package 110 b aligned with thesecond package bond sites 113 of the first package 110 a. When solderballs 101 are used to connect the packages 110 a, 110 b, a reflowoperation can be used to connect the solder between the two sets ofpackage bond sites 112, 113.

One feature of at least some of the embodiments described above withreference to FIGS. 1-3G is that each package 110 can include a singlesupport member 130, and an arrangement of stacked packages can includeas many support members as there are packages 110. This is unlike someexisting arrangements for stacking microelectronic dies, in whichadditional support members are used to provide the interconnectionsbetween stacked dies. Unlike these arrangements, embodiments such asthose described above with reference to FIGS. 1-3G have no supportmember positioned between the leadframe and the microelectronic diewithin a given package. An advantage of reducing the number of supportmembers included in the package (or package stack) is that it can reducethe overall thickness of the stack and therefore the volume occupied bythe stack when it is installed in a product (e.g., a computer, cellphone, video device, etc.).

Another feature of at least some of the embodiments described above withreference to FIGS. 1-3G is that they can include leadfingers 141 havingbonding surfaces that project away or are offset from the parallelleadfinger surface that faces in the same direction (e.g., the firstleadfinger surface 142 a shown in FIG. 2B). This arrangement allows theleadfingers 141 (and in particular, the second package bond sites 113)to be accessible from the surface of the package that faces opposite thefirst package bond sites 112. As a result, the packages may be readilystacked on one another.

Another feature of at least some of the embodiments described above withreference to FIGS. 1-3G is that each package has a volume of encapsulantthat is separate from and not integrated with the encapsulant of theother. Accordingly, the packages can be attached to each other and, ifnecessary, separated from each other at the junctions between the firstpackage bond sites of one package and the second package bond site ofthe other. This feature allows the packages to be separated (forexample, if one package fails), without having to disturb theencapsulant of either package.

FIGS. 4-8 illustrate packages with microelectronic dies and encapsulatedleadframes configured in accordance with further embodiments of theinvention. For example, FIG. 4 illustrates a package 410 that includes amicroelectronic die 420 carried by a support member 430 having supportmember bond sites 433. Unlike the arrangement shown in FIG. 1, die bondsites 421 of the microelectronic die 420 face away from the supportmember bond sites 433 and are connected to the support member bond sites433 with wire bonds 422 that do not extend through an opening in thesupport member 430. The package 410 also includes a leadframe 440 havingleadfingers 441 that extend not only over the die 420, but also over thewirebonds 422. Other aspects of the package 410 can be generally similarto those described above with reference to FIG. 1. For example, thesupport member 430 can include support member circuitry 431 that couplesthe support member bond sites 433 to first package bond sites 412 and toleadframe bond sites 432. The leadframe 440 can carry second packagebond sites 413 that are accessible through a surrounding body ofencapsulant 411 for electrical coupling to the package 410.

FIG. 5 is a top plan view of a package 510 having an arrangementsomewhat similar to that described above with reference to FIG. 4, butwith the wirebonds oriented in a different direction from, and notdirectly underneath, the leadfingers. For example, the package 510 caninclude a support member 530 carrying a microelectronic die 520 havingdie bond sites 521 positioned toward the ends of the die 520 andconnected to support member bond sites 533 positioned toward the ends ofthe corresponding support member 530. The support member bond sites 533are connected to leadframe bond sites 532 with internal circuitry (notshown) within the support member 530. The leadframe 540 can includeleadfingers 541 that are electrically bonded to the leadframe bond sites532, and that extend over the orthogonally located sides of the die 520,so as not to pass directly over the wirebonds 522. The leadfingers 541can include second package bond sites 513 that are accessible forcoupling in a manner generally similar to that described above.Orienting the leadfingers 541 away from the wirebonds 522 avoidsphysical interference between these elements, and can also reduce oreliminate electrical interference between these elements.

FIG. 6 illustrates a package 610 that includes a support member 630carrying a die 620 that is electrically coupled to the support member630 via solder balls 601. Accordingly, the die 620 can include die bondsites or bond pads 621 that face toward corresponding support memberbond sites 633, with the solder balls 601 positioned in between. Some ofthe die bond sites 621 and support member bond sites 633 may be offsetfrom the plane of FIG. 6 and therefore not visible. The support memberbond sites 633 can be coupled to first package bond sites 612 andleadframe bond sites 632 in a manner generally similar to that describedabove. A leadframe 640 can be attached to the leadframe bond site 632and can carry second package bond sites 613 positioned to face in adirection opposite that of the first package bond sites 612, also in amanner generally similar to that described above.

FIG. 7 is a partially schematic, cross-sectional side view of a package710 that includes multiple microelectronic dies positioned within thesame volume of encapsulant, and electrically coupled to the sameleadframe 740. For example, the package 710 can include twomicroelectronic dies 720, shown as a first microelectronic die 720 a anda second microelectronic die 720 b, stacked one upon the other, with thesecond microelectronic die 720 b positioned between the first die 720 aand a support member 730. The second microelectronic die 720 b caninclude die bond sites 721 b that are electrically coupled to thesupport member 730 in a manner generally similar to that described abovewith reference to FIG. 6. The first microelectronic die 720 a caninclude die bond sites 721 a that are electrically coupled to thesupport member 730 in a manner generally similar to that described abovewith reference to either FIG. 4 or FIG. 5. The internal circuitry withinthe support member 730 can couple first support member bond sites 733 aand second support member bond site 733 b to first package bond sites712 and to leadframe bond sites 732. A leadframe 740 having secondpackage bond sites 713 is electrically connected to the leadframe bondsites 732 and extends over the composite of the first microelectronicdie 720 a and the second microelectronic die 720 b. Accordingly, anadvantage of an arrangement shown in FIG. 7 is that the overallthickness of the composite may be less than the thickness of the stackeddie arrangement shown in FIG. 1. Conversely, an advantage of anembodiment shown in FIG. 1 is that each microelectronic die can beindividually tested prior to stacking the packages shown in the manneras shown in FIG. 1.

FIG. 8 is a partially schematic, cross-sectional side view of a package810 having first and second microelectronic dies 820 a, 820 b arrangedin generally the opposite fashion from that shown in FIG. 7.Accordingly, the second die 820 b can be connected to the correspondingsupport member 830 with wire bonds 822, and the first die 820 a can becoupled to the second die 820 b with solder balls 801. In a particularaspect of this embodiment, the second die 820 b can include second diebond sites 821 b and redistribution lines 823 that connect the seconddie bond sites 821 b with intermediate bond sites 824. The first die 820a can be connected directly to the second die bond sites 821 b with thesolder balls 801, and the second die 820 b can be connected to thesupport member 830 with wire bonds 822 connected between theintermediate bond sites 824 and corresponding support member bond sites833. The support member bond sites 833 can be coupled to first packagebond sites 812 and leadframe bond sites 832 via support member circuitry831. The leadframe bond sites 832 are in turn connected to secondpackage bond sites 813 via a corresponding leadframe 840.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thescope of the invention. For example, the microelectronic dies can haveconfigurations other than those shown in the Figures and/or can becombined in manners other than those shown in the Figures. In certainembodiments, when packages are stacked on each other, they need not havethe same configuration. For example, the upper package may have nosecond package bond sites, a different leadframe arrangement than thatof the lower package, or no leadframe at all. The bond sites, electricalcouplers and circuitry can be arranged and/or combined in manners otherthan those discussed above and shown in the Figures. Although advantagesassociated with certain embodiments of the invention have been describedin the context of those embodiments, other embodiments may also exhibitsuch advantages. Additionally, none of the foregoing embodiments neednecessarily exhibit such advantages to fall within the scope of theinvention. Accordingly, the invention is not limited except as by theappended claims.

I/We claim:
 1. A microelectronic die system, comprising: a supportmember having first package bond sites and leadframe bond sites that areelectrically coupled to the first package bond sites; a microelectronicdie carried by the support member and electrically coupled to the firstpackage bond sites; a leadframe attached to the leadframe bond sites andextending adjacent to the microelectronic die, with the microelectronicdie positioned between the leadframe and the support member, theleadframe having second package bond sites facing away from the firstpackage bond sites; and an encapsulant at least partially surroundingthe leadframe and the microelectronic die, with the first and secondpackage bond sites accessible from outside the encapsulant.
 2. Thesystem of claim 1 wherein the first and second package bond sites bothhave generally flat bonding surfaces.
 3. The system of claim 1 whereinthe leadframe is attached directly to the microelectronic die with anadhesive.
 4. The system of claim 1 wherein the leadframe isself-supporting.
 5. The system of claim 1 wherein no support member isinterposed between the leadframe and the microelectronic die.
 6. Thesystem of claim 1 wherein the second bond sites face away from themicroelectronic die.
 7. The system of claim 1 wherein themicroelectronic die is electrically connected to the support member withwirebonds.
 8. The system of claim 1 wherein the microelectronic die iselectrically connected to the support member with solder balls.
 9. Thesystem of claim 1 wherein the microelectronic die is the first of twomicroelectronic dies carried by the support member, and wherein both thefirst and second microelectronic dies are positioned between the supportmember and the leadframe.
 10. The system of claim 9 wherein the firstmicroelectronic die is positioned adjacent to the leadframe and thesecond microelectronic die is positioned between the firstmicroelectronic die and the support member, and wherein the secondmicroelectronic die is electrically connected to the support member withwirebonds, and the first microelectronic die is electrically connectedto the second microelectronic die with solder.
 11. The system of claim 9wherein the first microelectronic die is positioned adjacent to theleadframe and the second microelectronic die is positioned between thefirst microelectronic die and the support member, and wherein the secondmicroelectronic die is electrically connected to the support member withsolder balls, and the first microelectronic die is electricallyconnected to the support member with wirebonds.
 12. The system of claim1 wherein the microelectronic die has a first surface facing toward thesupport member and a second surface facing away from the support memberand toward the leadframe, and wherein the microelectronic die iselectrically coupled to the first package bond sites via wirebondsconnected to die bond pads accessible from the first surface of themicroelectronic die.
 13. The system of claim 1 wherein themicroelectronic die has a first surface facing toward the support memberand a second surface facing away from the support member and toward theleadframe, and wherein the microelectronic die is electrically coupledto the first package bond sites via wirebonds connected to die bond padsaccessible from the second surface of the microelectronic die.
 14. Thesystem of claim 1 wherein the support member, the microelectronic die,the leadframe and the encapsulant form a first microelectronic package,and wherein the system further comprises a second microelectronicpackage stacked on the first and electrically connected to the secondpackage bond sites of the first microelectronic package.
 15. The systemof claim 14 wherein the second microelectronic package does not havesecond package bonds accessible for electrical coupling.
 16. The systemof claim 14 wherein the second microelectronic package has aconfiguration generally similar to that of the first microelectronicpackage.
 17. The system of claim 14 wherein the second microelectronicpackage has a configuration generally similar to that of the firstmicroelectronic package, but with second package bond sites that are notaccessible for electrical coupling.
 18. The system of claim 1 whereinindividual leadfingers of the leadframe have a leadfinger surface facingin a first direction and located in a leadfinger plane, wherein thesecond package bond sites are offset away from the leadfinger plane inthe first direction.
 19. The system of claim 18 wherein the leadfingersurface is a first leadfinger surface, and wherein the individualleadfingers have a generally flat second leadfinger surface facing in asecond direction opposite the first direction.
 20. The system of claim 1wherein the leadframe does not have wire bonds connected to it.
 21. Thesystem of claim 20 wherein the microelectronic die is electricallycoupled to the support member with wire bonds.
 22. The system of claim 1wherein the support member includes a circuit board.
 23. The system ofclaim 1 wherein the support member is the only support member within theencapsulant.
 24. The system of claim 1 wherein the leadframe isgenerally encased by the encapsulant except at the second package bondsites.
 25. The system of claim 1, further comprising an external deviceconnected to the first package bond sites.
 26. A microelectronic diesystem, comprising: first and second microelectronic die packages, eachhaving: a support member having first package bond sites and leadframebond sites that are electrically coupled to the first package bondsites; a microelectronic die carried by the support member andelectrically coupled to the first package bond sites; a leadframeattached to the leadframe bond sites and extending adjacent to themicroelectronic die, with the microelectronic die positioned between theleadframe and the support member, the leadframe having second packagebond sites facing away from the first package bond sites; and anencapsulant at least partially surrounding the leadframe and themicroelectronic die; wherein at least the first microelectronic diepackage has both the first and second package bond sites accessible fromoutside the encapsulant and wherein the second microelectronic diepackage is stacked relative to the first microelectronic die package,with the first package bond sites of the second microelectronic diepackage electrically connected to the second package bond sites of thefirst microelectronic die package.
 27. The system of claim 26 whereinthe encapsulant of the first microelectronic die package is notintegrated with the encapsulant of the second microelectronic diepackage, and wherein the first and second microelectronic die packagesare attachable to and separable from each other at junctions between thefirst package bond sites of the second microelectronic die package andthe second package bond sites of the first microelectronic die package.28. The system of claim 26 wherein the second microelectronic packagedoes not have second package bonds accessible for electrical coupling.29. The system of claim 26 wherein the second microelectronic packagehas a configuration generally similar to that of the firstmicroelectronic package.
 30. The system of claim 26 wherein the secondmicroelectronic package has a configuration generally similar to that ofthe first microelectronic package, but with second package bond sitesthat are not accessible for electrical coupling.
 31. The system of claim26 wherein the second microelectronic package has a configurationgenerally identical to that of the first microelectronic package, butwith second package bond sites that are not accessible for electricalcoupling.
 32. The system of claim 26 wherein the leadframe does not havewire bonds connected to it.
 33. The system of claim 32 wherein themicroelectronic die is electrically coupled to the support member withwire bonds.
 34. The system of claim 26 wherein the support memberincludes a circuit board.
 35. The system of claim 26 wherein the supportmember is the only support member within the encapsulant.
 36. The systemof claim 26 wherein the leadframe is generally encased by theencapsulant except at the second package bond sites.
 37. The system ofclaim 26 wherein individual leadfingers of the leadframe have aleadfinger surface facing in a first direction and located in aleadfinger plane, wherein the second package bond sites are offset awayfrom the leadfinger plane in the first direction.
 38. A leadframe forelectrical coupling to a microelectronic die, comprising: a conductiveframe; and a plurality of conductive leadfingers connected to andextending inwardly from the frame, individual leadfingers having aleadfinger surface facing in a first direction and located in aleadfinger plane, the individual leadfingers further having anelectrically conductive bond site with a bonding surface that is offsetaway from the leadfinger plane in the first direction.
 39. The leadframeof claim 38 wherein the leadfinger surface is a first leadfinger surfacefacing in the first direction, and wherein the individual leadfingershave a second leadfinger surface facing opposite from the firstleadfinger surface, the second leadfinger surface being generally flatand uniform.
 40. The leadframe of claim 38 wherein the conductive bondsite and the bonding surface are integral elements of the leadfingers.41. The leadframe of claim 38 wherein the conductive frame forms anenclosed region within which the leadfingers are positioned.
 42. Theleadframe of claim 38, further comprising electrically conductivecouplers attached to individual bond sites.
 43. The leadframe of claim42 wherein the conductive couplers include solder balls.
 44. A methodfor making a microelectronic die system, comprising: carrying amicroelectronic die with a support member, the support member havingfirst package bond sites and leadframe bond sites that are electricallycoupled to the first package bond sites; electrically coupling themicroelectronic die to the first package bond sites; positioning theleadframe adjacent to the microelectronic die, with the microelectronicdie located between the leadframe and the support member, and withsecond package bond sites of the leadframe facing away from themicroelectronic die; electrically connecting the leadframe to theleadframe bond sites; at least partially surrounding the leadframe andthe microelectronic die with an encapsulant; and allowing access to thefirst and second package bond sites from outside the encapsulant. 45.The method of claim 44, further comprising attaching the leadframe tothe microelectronic die with an adhesive positioned between theleadframe and the microelectronic die.
 46. The method of claim 44wherein allowing access to the second package bond sites includesremoving encapsulant from adjacent to the second package bond sites. 47.The method of claim 46 wherein removing the encapsulant includesgrinding the encapsulant to expose the second package bond sites. 48.The method of claim 44 wherein allowing access to the second packagebond sites includes at least restricting the encapsulant from beingdisposed adjacent to the second package bond sites.
 49. The method ofclaim 44 wherein allowing access to the second package bond sitesincludes allowing access to bonding surfaces of the second bond sitesthat project away from adjacent surfaces of the leadframe so that theadjacent surfaces are enclosed by the encapsulant while the bondingsurfaces are exposed.
 50. The method of claim 44 wherein electricallycoupling the microelectronic die to the first package bond sitesincludes electrically coupling the microelectronic die to support memberbond sites that are in turn electrically coupled to the first packagebond sites.
 51. The method of claim 44 wherein positioning the leadframeincludes positioning the leadframe with no support member interposedbetween the leadframe and the microelectronic die.
 52. The method ofclaim 44 wherein electrically coupling the microelectronic die to thefirst package bond sites includes electrically connecting themicroelectronic die to the support member with wirebonds.
 53. The methodof claim 44 wherein the microelectronic die is the first of twomicroelectronic dies carried by the support member, and wherein themethod further comprises positioning both the first and secondmicroelectronic dies between the support member and the leadframe. 54.The method of claim 53 wherein the first microelectronic die ispositioned adjacent to the leadframe and the second microelectronic dieis positioned between the first microelectronic die and the supportmember, and wherein the method further comprises: electricallyconnecting the second microelectronic die to the support member withwirebonds; and electrically connecting the first microelectronic die tothe second microelectronic die with solder.
 55. The method of claim 53wherein the first microelectronic die is positioned adjacent to theleadframe and the second microelectronic die is positioned between thefirst microelectronic die and the support member, and wherein the methodfurther comprises: electrically connecting the second microelectronicdie to the support member with solder balls; and electrically connectingthe first microelectronic die to the support member with wirebonds. 56.The method of claim 44 wherein the support member, the microelectronicdie, the leadframe and the encapsulant form a first microelectronicpackage, and wherein the method further comprises: stacking a secondmicroelectronic package relative to the first microelectronic package;and electrically connecting package bond sites of the secondmicroelectronic package to the second package bond sites of the firstmicroelectronic package.
 57. The method of claim 56 wherein stacking asecond microelectronic package includes stacking a secondmicroelectronic package that has first package bond sites accessible forelectrical coupling, but does not have second package bond sitesaccessible for electrical coupling, and wherein electrically connectingthe package bond sites of the second microelectronic package includeselectrically connecting the first package bond sites of the secondmicroelectronic package to the second package bond sites of the firstmicroelectronic package.
 58. The method of claim 56, further comprisingelectrically testing microelectronic dies of the first and secondmicroelectronic packages after each has been encapsulated and beforestacking the second microelectronic package relative to the first. 59.The method of claim 44 wherein stacking a second microelectronic packageincludes stacking a second microelectronic package having aconfiguration at least generally similar to a configuration of the firstmicroelectric package.
 60. The method of claim 44, further comprisingproviding an electrical connection between the microelectronic die andthe leadframe without connecting wire bonds directly to the leadframe.61. The method of claim 44 wherein carrying the microelectronic die witha support member includes carrying the microelectronic die with asupport member that includes a circuit board.
 62. The method of claim 44wherein at least partially surrounding the leadframe and themicroelectronic die with the encapsulant includes at least partiallysurrounding the support member with the encapsulant, with the supportmember being the only support member within the encapsulant.
 63. Amethod for forming a leadframe for electrical coupling to amicroelectronic die, comprising: providing a conductive leadframe havinga plurality of conductive leadfingers extending inwardly from a frame,with individual leadfingers having a leadfinger surface facing in afirst direction and located in a leadfinger plane; and for individualleadfingers, forming a bond site with a bonding surface that faces in afirst direction and that is offset in the first direction away from aplane containing an immediately adjacent surface of the leadfinger thatalso faces in the first direction.
 64. The method of claim 63 whereinthe leadfinger surface is a first leadfinger surface facing in the firstdirection, and wherein providing the conductive leadframe includesproviding the conductive leadframe with the individual leadfingershaving a second leadfinger surface facing opposite from the firstleadfinger surface, the second leadfinger surface being generally flatand uniform.
 65. The method of claim 63, further comprising forming thebond sites to be integral portions of the leadfingers.
 66. The method ofclaim 63 wherein forming the bond site includes removing material fromthe immediately adjacent surface of the leadfinger so that the bondingsurface projects away from the immediately adjacent surface.
 67. Themethod of claim 63, further comprising connecting electricallyconductive couplers attached to individual bond sites.
 68. The method ofclaim 67 wherein connecting electrically conductive couplers includeconnecting solder balls.
 69. The method of claim 63, further comprising:at least partially encapsulating the leadframe and a microelectronicdie; and allowing access to the bonding surfaces.
 70. The method ofclaim 69 wherein allowing access to the bonding surfaces includesremoving encapsulating material overlying the bonding surfaces.